Humidity control and air conditioning

ABSTRACT

Air conditioning systems that cool and dehumidify spaces within enclosures, buildings having such systems, and methods of controlling humidity within a space. Embodiments adjust speed of a blower or fan motor based on inputs from sensors within the system, using automated processes, to reduce airflow rates to provide for lower temperatures of the cooling coil and to increase the ratio of latent to sensible heat transfer. Fan speeds may be increased as appropriate to avoid frost formation on the cooling coil, to give priority to cooling when temperatures within the space are high, or periodically to provide for mixing within the space.

FIELD OF INVENTION

This invention relates to systems and methods for controlling humidity,heating, ventilating, and air-conditioning (HVAC) equipment, systems andmethods, and control equipment. Specific embodiments relate tomass-produced air conditioning units, for example, for residentialapplications, and to their controls.

BACKGROUND OF THE INVENTION

Heating, ventilating, and air-conditioning (HVAC) systems have been usedto ventilate and maintain desirable temperatures within spaces such asbuildings, for occupants to live and work, for example. Air conditioningunits have been known to remove humidity from the air, as well asreducing the temperature of the air, and humidity reduction hascontributed to making spaces within enclosures more comfortable,particularly in hot and humid climates or conditions. However, it hasalso been known that humidity can cause frost formation on evaporatorcoils, and such frost formation has, on more than one occasion, blockedairflow through the evaporator coil, reduced the effectiveness of heattransfer to an evaporator coil, or both. Further, it has been known thatfrost formation on evaporator coils can, in many cases, be avoided bymaintaining adequate air flow through the evaporator coils so that thetemperature of the evaporator coil remains above or substantially abovea freezing temperature. Accordingly, in many air conditioning units,blowers have been sized to provide adequate flow to prevent frostformation on evaporator coils.

In addition, certain HVAC units have been used that have had variablespeed fans or blowers. Some such systems have been used in variable airvolume (VAV) systems, for example, and have used variable speed driveunits, such as variable frequency AC drive units or variable voltage DCsystems. However, even variable-speed blowers have typically beenoperated at high-enough speeds to maintain evaporator temperatures wellabove freezing.

Air conditioning units typically use a significant amount of energy intheir operation, and steps have been taken to improve the energyefficiency or coefficient of performance of air conditioning units,including units for residential applications, for instance. One changethat has been made to air conditioning units to improve the coefficientof performance has been to increase the surface area of the indoor coilor evaporator coil, and the supply airflow rate relative to the totalamount of heat transfer. This results in a higher evaporator or coolingcoil temperature generally. Although coefficient of performance istypically improved by these changes, due to the higher airflow ratesrelative to the total amount of heat transfer, air temperatures (e.g.,of supply air) are not reduced as much, and humidity levels in the spacetypically are not reduced as much as a result. Such increases inhumidity levels may be acceptable if humidity levels are not very highto start with; however, needs or potential for benefit exist for HVACequipment, systems, and methods that provide for greater humidityreduction, for example, when humidity levels are excessive.

Needs or potential for benefit exist for equipment, systems, and methodsthat at least partially compensate for changes in humidity levels, forexample, selecting priorities between emphasizing or maximizingcoefficient of performance and emphasizing or maximizing humidityreduction. In addition, in at least some applications, needs orpotential for benefit exist for systems or methods that emphasizecapacity (e.g., total heat transfer) when temperatures are excessive,but that may emphasize humidity reduction (e.g., if humidity levels areexcessive) when temperatures are closer to desired values. Further,needs or potential for benefit exist for such equipment, systems, andmethods that are inexpensive, utilize existing components (e.g., to agreater degree than alternatives), are reliable, are easy to place intoservice by typical installation personnel, or a combination thereof.Needs or potential for benefit exist for such equipment, systems, andmethods in typical residential applications, for example, such asmass-produced residential air-conditioning units, heat pumps, furnaces,and the like, that are suitable to be installed by typical installers ofsuch equipment. Potential for improvement exists in these and otherareas that may be apparent to a person of skill in the art havingstudied this document.

SUMMARY OF PARTICULAR EMBODIMENTS OF THE INVENTION

This invention provides, among other things, air conditioning units andsystems that cool and dehumidify spaces within enclosures, and methodsof controlling humidity within a space, for example, using an airconditioning unit or system. Different embodiments adjust or vary speedor torque of a blower or fan motor based on inputs from sensors withinthe system, using automated processes, or both, for example. Variousembodiments of the invention provide as an object or benefit that theypartially or fully address one or more of the needs, potential areas forimprovement or benefit, or functions described herein, for instance.Specific embodiments provide as an object or benefit, for instance, thatthey at-least partially provide for control of humidity within a space,provide for control of HVAC equipment or systems, or provide specificair conditioning systems, equipment, or units, or a combination thereof,for example. In many embodiments, a controller is used to controlvarious equipment, and such a controller may be a digital controller,for example. In some embodiments, an object or benefit is to controlhumidity while avoiding frost formation on a cooling coil, as anotherexample. Various embodiments reduce airflow rates under appropriateconditions to provide for lower temperatures of the cooling coil andsupply air to reduce humidity. Fan speeds may be increased underappropriate conditions to avoid frost formation on the cooling coil, togive priority to cooling when temperatures within the space are high, orperiodically to provide for mixing within the space, as examples.

Various embodiments provide equipment, systems, and methods that arereasonably inexpensive, utilize existing components to at least somedegree, are reasonably reliable, and can reasonably be placed intoservice by typical installation personnel, for example, typical servicepersonnel in residential installations. Further still, particularembodiments provide equipment, systems, and methods that control ormaintain (at least to some extent) humidity within desired ranges ortoward desired goals. Different embodiments may provide for reducedenergy consumption in comparison with certain alternatives, may providefor reduced noise, may avoid insufficient or excessive airflow rates,may provide for sufficient airflow through evaporator coils to preventfrost formation, or a combination thereof, as further examples.

In specific embodiments, this invention provides air conditioningsystems for cooling and dehumidifying a space within an enclosure. Suchair conditioning systems include a cooling coil positioned within thesystem and configured to cool air to be delivered from the airconditioning system to the space, a first fan positioned and configuredto move the air through the cooling coil and to the space, a firstelectrical motor connected to and configured to turn the first fan, anda first variable-speed drive system configured and at least electricallyconnected to drive the first electrical motor. These air conditioningsystems also include a first sensor positioned and configured to sense afirst condition within the space or the air, and the first conditioncomprises a humidity. Such air conditioning systems also include asecond sensor positioned and configured to sense a second condition atthe cooling coil, and a controller that is in communication with thefirst variable-speed drive system and in communication with the firstsensor and the second sensor. In these embodiments, the controller isconfigured to cause the first variable-speed drive system to change thespeed of the first electrical motor in response to the first conditionsensed by the first sensor and in response to the second conditionsensed by the second sensor.

In some such embodiments, the second condition is the temperature at thecooling coil, for example. In addition, in a number of theseembodiments, the controller is configured to cause the firstvariable-speed drive system to reduce the speed of the first electricalmotor in response to an excessive humidity condition sensed by the firstsensor. Furthermore, in certain embodiments, the controller isconfigured to cause the first variable-speed drive system to stopreducing the speed of the first electrical motor to avoid frostformation on the cooling coil, and in some embodiments, the controlleris configured to cause the first variable-speed drive system to actuallyincrease the speed of the first electrical motor to avoid frostformation on the cooling coil.

In various of these embodiments, the cooling coil is an evaporator coil,and the air conditioning system further comprises, within a singleenclosure for the air conditioning system, an expansion valve, acompressor, an electric second motor connected to and configured to turnthe compressor, a condenser coil, a second fan configured to blow airthrough the condenser coil, and an electric third motor connected to andconfigured to turn the second fan. Still further, some embodimentsfurther include a third sensor positioned and configured to sense athird condition within the space or the air, and this third conditionmay be a temperature within the space or the air, for example. In somesuch embodiments, the controller is in communication with the thirdsensor and is further configured to forgo causing the firstvariable-speed drive system to reduce the speed of the first electricalmotor in response to the first condition sensed by the first sensor ifthe third condition exceeds a threshold. In certain embodiments, thethird sensor includes, or is part of, a system controller located withinthe space, and in some embodiments the threshold is relative to atemperature set point of the system controller.

Other embodiments of the invention are (or include) a building thatincludes at least one embodiment of the air conditioning systemdescribed above, and the building forms the enclosure in many suchembodiments. Still other specific embodiments include various methods ofcontrolling humidity within a space. Certain such methods include (e.g.,at least) the act or activity of providing or obtaining anair-conditioning unit that includes a cooling coil and a variable-speedfan, wherein the fan is positioned and configured to move air throughthe cooling coil to the space. These methods also include the acts oractivities of measuring humidity using an automated process to obtain ahumidity measurement, and using an automated process, using the humiditymeasurement to determine whether to reduce the humidity. Such methodsalso include the acts or activities of using an automated process, anddependent upon the humidity measurement, lowering the speed of the fanto decrease the cooling coil temperature, thus increasing the latentcomponent of energy absorption at the cooling coil, resulting in areduction of the humidity relative to a humidity level that would haveresulted from not lowering the speed of the fan. These examples ofmethods also include the acts of using an automated process, measuring asecond condition at the cooling coil, and using an automated process,controlling the speed of the fan using the second condition to avoidfrost formation on the cooling coil.

A number of these methods further include the act of, using an automatedprocess, measuring a first temperature within the space, and the act ofreducing of the speed of the fan is performed only if the firsttemperature is below a first threshold temperature. In addition, in someembodiments, the second condition is a temperature of the cooling coiland the speed of the fan is controlled using the second temperature toavoid having the second temperature drop below freezing. Further,certain of these methods further include the act of repeating at least aplurality of times the lowering of the speed of the fan, which isperformed in discrete increments wherein the speed of the fan is heldsubstantially constant for a period of time for each of the distinctincrements. The act of measuring the temperature of the cooling coilduring each period of time may also be repeated, and the lowering of thespeed of the fan may be performed in a subsequent discrete incrementonly if the temperature of the cooling coil is above a first temperaturethreshold. Even further, some embodiments further include an act ofraising of the speed of the fan, which may be performed in discreteincrements, and the speed of the fan may be held substantially constantfor a period of time for each of the distinct increments. Thetemperature of the cooling coil may be measured during each period oftime, and the raising of the speed of the fan may be performed in asubsequent discrete increment only if the temperature of the coolingcoil is below a second temperature threshold.

Still other embodiments of the invention include, as another example,particular methods of controlling humidity within a space using anair-conditioning unit. Such an air conditioning unit may include acooling coil and a variable-speed fan, and the fan may blows air throughthe cooling coil. Such methods include (e.g., in any order) acts oractivities of receiving a temperature set point for the space, measuringan actual temperature within the space, evaluating whether the actualtemperature within the space is within a predetermined offset of thetemperature set point, and measuring an actual humidity in the space orair drawn from the space. Such methods also include acts of evaluatingwhether the actual humidity exceeds a predetermined humidity threshold,and if, and only if, the actual temperature within the space is withinthe predetermined offset of the temperature set point, and the actualhumidity exceeds the predetermined humidity threshold, lowering thespeed of the fan to reduce the humidity.

Some of these methods further include acts of monitoring at least afirst condition of the cooling coil and increasing the speed of the fanto avoid freezing of the cooling coil, and in particular embodiments theact of monitoring of the first condition of the cooling coil comprisesmonitoring of a temperature at the cooling coil. In addition, in anumber of embodiments, the act of lowering the speed of the fan includes(e.g., in the following order), the acts of lowering the speed by adiscrete speed increment, operating the fan at a substantially constantspeed for a discrete increment of time, measuring the first condition,and repeating the lowering of the speed by a discrete speed increment,operating of the fan at a substantially constant speed for a discreteincrement of time, and measuring of the first condition, until the firstcondition reaches a first threshold value.

In some embodiments, the act of increasing the speed of the fancomprises the acts of increasing the speed by a discrete speedincrement, operating the fan at a substantially constant speed for adiscrete increment of time, measuring the first condition, and repeatingthe increasing of the speed by a discrete speed increment, operating thefan at a substantially constant speed for a discrete increment of time,and measuring the first condition, until the first condition reaches asecond threshold value. Further, in various embodiments. the firstcondition includes (or is) a temperature at the first coil, the firstthreshold value is a first temperature above freezing and the secondthreshold value is a second temperature above the first temperature.Still further, some such methods further include the acts of increasingthe speed of the fan after a first time period to insure proper airdistribution within the space, and then returning after a second timeperiod to the lowering of the speed of the fan to reduce the humidity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating, among other things, an airconditioning unit and system, installed on a building, that illustratesvarious examples of embodiments of the invention; and

FIG. 2 is a flow chart illustrating examples of various methods,including, as examples, methods of controlling humidity within a space.

The drawings illustrate, among other things, various particular examplesof embodiments of the invention, and certain examples of characteristicsthereof. Different embodiments of the invention include variouscombinations of elements or activities shown in the drawings, describedherein, known in the art, or a combination thereof.

DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENTS

In a number of embodiments, this invention provides improvements toheating, ventilating, and air-conditioning (HVAC) systems, buildingshaving such systems, methods, and controls. Various embodiments adjustor vary speed or torque of a blower or fan motor based on inputs fromsensors within the system, using automated processes, or both, forexample. Various embodiments at-least partially provide for control ofhumidity within a space, provide for control of HVAC equipment orsystems, or provide specific air conditioning systems, equipment, orunits, or a combination thereof, for example. In many embodiments, acontroller is used to control certain equipment, and such a controllermay be a digital controller, for example. Some embodiments controlhumidity while avoiding frost formation on a cooling coil.

In some embodiments, air conditioning units may be mass produced incommon configurations and installed in different buildings orstructures. In such applications, airflow rates may be controlled to atleast partially control humidity levels. In particular embodiments, forexample, the speed, torque, or both, of a fan motor may be varied toobtain a desired humidity level, a humidity level that is within aparticular range, or a more desirable humidity level. Such a process maybe automated, continuous, or both, in various embodiments. Variousembodiments adjust speed of a blower or fan motor based on inputs fromsensors within the system, using automated processes, to reduce airflowrates to provide for lower temperatures of the cooling coil and supplyair to reduce humidity. Fan speeds may be increased to avoid frostformation on the cooling coil, to give priority to cooling whentemperatures within the space are high, or periodically to provide formixing within the space, as examples.

FIG. 1 illustrates an example of both embodiments of the invention andan environment in which embodiments of the invention may be used. Inthis embodiment, air-handling unit or air conditioning unit 10 is usedfor ventilating an at-least partially enclosed space 11. In addition, inthis embodiment, space 11 is enclosed by or within building or structure19, which may be a residence such as a single family house, anapartment, a portion of a duplex, triplex, or fourplex, or a cabin, ormay be a hotel room, a business establishment such as a store or arestaurant, or the like. Building 19 is an example of particularembodiments of the invention that are (or include) a building (e.g., 19)that includes at least one embodiment of the air conditioning unit(e.g., 10) or system (e.g., 10 s) described herein. The building 19forms the enclosure 11 in the embodiment illustrated. In manyembodiments, residential use is the predominant market for air handlingunit 10, for instance.

In this embodiment, air conditioning unit 10 includes a first fan 12 athat is configured to move or blow air through air conditioning unit 10and to space 11. In this embodiment, supply air 16 s is delivered tospace 11 through ductwork 16 a and registers 16 w, 16 x, and 16 y.Further, in this embodiment, return air 16 r is fed to air conditioningunit 10 through return air ductwork 16 b, filter 16 f, and grille 16 z,as may be found in a residential application, for example. In otherembodiments, fan 12 a may be fed with outside air, or a combination ofoutside and return air, for example. As would be apparent to a person ofordinary skill in the art, air handling unit 10 and structure 19 are notshown to scale relative to each other in FIG. 1, and other componentsillustrated may also not be shown to scale. Fan 12 a, in differentembodiments, may be an axial or propeller-type fan (as shown), acentrifugal fan [e.g., with forward curved (e.g., a squirrel cage fan)or backward curved vanes (e.g., airfoil shaped)], or a mixed flow fan,as examples.

In the embodiment illustrated, air-handling or air conditioning unit 10,ductwork 16 a and 16 b, registers 16 w, 16 x, and 16 y, filter 16 f,grille 16 z, and thermostat 16 t, form ventilation system 10 s. In thisembodiment, within air conditioning unit 10, electric first motor 13 ais connected to and configured to turn first fan 12 a. As used herein,“connected to and configured to turn” includes through a common rotatingshaft (as illustrated), directly coupled, through a belt drive (e.g.,which may have an adjustable sheave or pulley), or integral (e.g., anintegral fan and motor), for example. In this example of an embodiment,motor 13 a is driven or powered by drive unit 15 through leads 15 a and15 b. Drive unit 15 may be an electronic control module, for example. Insome embodiments, motor 13 a is an alternating current (AC) motor, anddrive unit 15 is a variable frequency drive unit, for example. In suchembodiments, motor 13 a may be a two-phase motor and may have two leads15 a and 15 b (as shown) or may have three or more phases and acorresponding number of leads, in other embodiments, as other examples.In AC embodiments, drive unit 15 may be configured to produce a varyingfrequency AC power supply to motor 13 a through leads 15 a and 15 b tocontrol the speed of motor 13 a and fan 12 a, for instance.

In other embodiments, motor 13 a may be a direct current (DC) motor anddrive unit 15 may be a DC power supply, which may be configured toproduce a varying DC output voltage to motor 13 a through leads 15 a and15 b to control the torque to, and therefore the speed of, motor 13 aand fan 12 a, for example. In still other embodiments, drive unit 15 maybe a variable frequency AC power supply, but may provide for control oftorque. In still other embodiments, drive unit 15 may be a DC powersupply, but may provide for control of speed. Although shown in FIG. 1as a separate components, in some embodiments, drive unit 15 may beintegral with motor 13 a.

Still referring to FIG. 1, drive unit 15, and thereby motor 13 a and fan12 a, may be controlled by control system or controller 14. In thisembodiment, drive unit 15 and controller 14 are shown as separatedevices; however, in other embodiments, drive unit 15 and controller 14may be integral, controller 14 may be part of drive unit 15, or driveunit 15 may be part of controller 14, as examples. Controller 14 mayinclude, or consist of, in some embodiments, an electronic boarddedicated for this purpose or combined with one or more other electronicboards such as a furnace, air handler, or thermostat board, as examples.In this embodiment, controller 14 is shown to be within enclosure 18 ofair conditioning unit 10, but in other embodiments, controller 14 may belocated elsewhere, for example, within structure 19, or within space 11.And in some embodiments, controller 14 may be combined with or integralto a thermostat (e.g., thermostat 14 t) or user-accessible controlpanel, for example. Further, in some embodiments, controller 14 may bedigital, and may include a digital processor, software, storage, memory,etc. Still further, in some embodiments, a user interface may beprovided which may include a keypad, a display, or the like. Such a userinterface may be part of controller 14, part of thermostat 14 t, or maybe a separate component, in various embodiments.

In a number of embodiments, controller 14 may output instructions todrive unit 15. In some embodiments, controller 14 outputs instructionsto other components of air conditioning unit 10 as well, or may haveother outputs, in addition to those described herein. Outputinstructions from controller 14 to drive unit 15 may be transmittedthrough data link 14 a, for instance, and may include, for example,input settings, which may include instructions for drive unit 15 tooperate motor 13 a at a particular speed or torque, for example. In someembodiments, controller 14 may instruct drive unit 15 to operate motor13 a at a particular AC frequency or at a particular DC voltage, asother examples. Data link 14 a (or other data links) may include one ormore conductors, which may communicate digital or analogue signals, forexample. These conductors may be insulated, shielded or both. In otherembodiments, data link 14 a may include a wireless connection,communication over power conductors, communication through a network,fiber-optic communication, or the like.

In a number of embodiments, controller 14 may also input data,measurements, or instructions from sensors or other devices and may usesuch inputs to calculate, select, or determine output instructions, suchas input settings for drive unit 15, for example, or speeds or torquesfor one or more motors (e.g., motor 13 a). Examples of such sensorsinclude temperature sensors, humidity sensors, pressure sensors (whichmay measure absolute pressure, gauge pressure, differential pressure, ora combination thereof), optical sensors, proximity probes, forcesensors, flow meters, conductivity or resistance sensor, etc. Sensorsmay convert parameters into an electrical signal, for example, ananalogue (e.g., a voltage, current, resistance, capacitance, etc.) ordigital signal, and such an electrical signal may be delivered, (e.g.,through one or more conductors or data links) to controller 14.

In some embodiments, including the embodiment illustrated in FIG. 1,air-handling unit 10 is an air conditioning unit having evaporator 15 e.Air handling unit 10 may be a vapor compression cycle unit, for example.Evaporator 15 e is an example of a heat-transfer coil configured andpositioned so that the air (e.g., return air 16 r) blown by first fan 12a through air-handling or air conditioning unit 10 passes through theheat-transfer coil (e.g., 15 e) (e.g., becoming supply air 16 s). Inthis example, wherein the heat-transfer coil is an evaporator (15 e), afluid (e.g., a refrigerant, such as Freon) passes through the firstheat-transfer coil, and heat is transferred via the heat-transfer coilbetween the air and the fluid. Thus, in a number of embodiments,air-handling unit 10 is an air conditioning unit, the fluid (e.g., thatpasses through the heat-transfer coil) is a refrigerant, and the firstheat-transfer coil is an evaporator coil or cooling coil (e.g., 15 e).In some embodiments, coil 15 e is a cooling coil when air conditioningunit 10 is operating in a cooling mode, but is a heating coil when airconditioning unit 10 is operating in a heating mode (e.g., as a heatpump).

In some other configurations, chilled water (e.g., cooled by a chiller)or (e.g., in a heating mode) heated water (e.g., heated with electricheat, by burning a fuel such as natural gas, propane, heating oil, wood,biomass, hydrogen, or coal, produced by solar energy, from a geothermalsource, produced as waste heat from an industrial process, produced asheat from cogeneration, or produced as waste heat from chillers or airconditioning units), or steam (e.g., produced similarly or in a boiler)are other examples of fluids that may pass through the heat-transfercoil (e.g., 15 e,) or another coil. Such a coil containing chilled wateris another example of a cooling coil.

In the particular embodiment illustrated, air conditioning unit 10further includes, within enclosure 18 for air conditioning unit 10,expansion valve 17 b, compressor 17 a, an electric second motor 13 cconnected to and configured to turn compressor 17 a, condenser coil 15c, second fan 12 b configured to blow air (e.g., outside air 160, whichbecomes exhaust air 16 e) through condenser coil 15 c, and electricthird motor 13 b connected to and configured to turn second fan 12 b.Air conditioning unit 10 is an example of a packaged air conditioningunit. In other embodiments, many similar components may be located in aseparate enclosure. For example, in some embodiments, (e.g., splitsystems) components analogous to expansion valve 17 b, compressor 17 a,electric second motor 13 c connected to and configured to turncompressor 17 a, condenser coil 15 c, second fan 12 b configured to blowair (e.g., outside air 160, which becomes exhaust air 16 e) throughcondenser coil 15 c, and electric third motor 13 b connected to andconfigured to turn second fan 12 b may be located in one or moreenclosures outside of structure 19. In such embodiments, componentsanalogous to evaporator 15 e, blower or fan 12 a, and motor 13 a, (or anumber of sets of such components) may be located inside structure 19,for example.

In many embodiments, motor 13 c may be a constant-speed motor, andcompressor 17 a may be operated at a constant speed. In other words, airconditioning unit 10 may be a constant capacity unit. In otherembodiments, compressor 17 a may have multiple speeds (e.g., 2, 3, 4, or5 speeds). In some embodiments, motor 13 c may be a variable-speedmotor, and compressor 17 a may be operated at variable speeds. In somesuch embodiments, compressor 17 a may be operated at continuouslyvarying speeds over a range of speeds, while in other embodiments,compressor 17 a may just be operated at particular speeds within a range(e.g., to avoid resonance frequencies). Further, in some situations,controller 14 may be used to control multiple motor blower assemblies(e.g., motor 13 a and fan 12 a being one example). In some applications,dip switches, jumpers, or both, may be mounted on the board, forexample, to select the desired assembly. In certain embodiments,communication between the control circuit (e.g., of controller 14) andthe motor (e.g., 13 a being an example) may be used to detect theassemblies.

Certain examples of embodiments of the invention include or providemass-produced air conditioning units (e.g., air conditioning unitembodiments of air-handling unit 10) for a variety of residentialstructures (e.g., an example of which is structure 19). Such airconditioning units may include, among other things, evaporator 15 e, fan12 a configured to blow air through the air conditioning unit (e.g.,through unit 10, evaporator 15 e, or both) to space 11, electric motor13 a connected to and configured to turn fan 12 a, and control system 14configured to use one or more inputs to control and vary the speed orthe torque of motor 13 a. In these embodiments, control system 14 may beconfigured to repeatedly or continuously (or both) sample one or moreinputs (e.g., from one or more sensors) and vary the speed or the torque(or both, e.g., power) of motor 13 a to control the airflow rate (e.g.,of supply air 16 s, return air 16 r, or both) through evaporator 15 e orthrough air conditioning unit 10. Different inputs may be used indifferent embodiments, and various examples are described herein.

In specific embodiments, air conditioning unit 10 or system 10 s may beused (possibly among other uses) for cooling and dehumidifying space 11within enclosure 19, for example. Such an air conditioning unit 10 orsystem 10 s includes, in this embodiment, evaporator or cooling coil 15e positioned within system 10 s (e.g., within unit 10 or enclosure 18)and configured to cool air (e.g., cool return air 16 r, which becomessupply air 16 s) to be delivered from air conditioning system 10 s tospace 11, first fan 12 a positioned and configured to move the air(e.g., return air 16 r, which becomes supply air 16 s) through coolingcoil 15 e and to space 11, first electrical motor 13 a connected to andconfigured to turn first fan 12 a, and a first variable-speed drive unitor system 15 configured and at least electrically connected to drive thefirst electrical motor 13 a.

In this particular embodiment, air conditioning unit 10 or system 10 salso includes a first sensor positioned and configured to sense a firstcondition within at least one of the space 11 and the air (e.g., returnair 16 r). In various embodiments, the first condition comprises ahumidity, for example, within space 11 or of return air 16 r. Twoexamples of such a first sensor include sensor 14 b and sensor 14 dshown in FIG. 1. Different embodiments of the invention may includesensor 14 b, sensor 14 d, or both, for example. Sensor 14 b may be ahumidity sensor located within space 11 within enclosure or building 19,and sensor 14 d may be a humidity sensor located within return air 16 rdrawn from space 11 via duct 16 b. Other embodiments may measurehumidity at another location, for example, within supply air 16 s (e.g.,downstream of evaporator or cooling coil 15 e, for instance, at thelocation represented by sensor 14 e). Such a humidity may be anindicator of moisture content within the air, and may be a relativehumidity, an absolute humidity, a dew point, or the like, as examples.Sensor 14 b, 14 d, or both, may be an electronic device, which mayoutput an electrical signal that represents or indicates such ahumidity, for example. In certain embodiments, sensor 14 b, 14 d, orboth, may be part of a greater device, which may measure otherparameters, input other values, perform other functions, or the like.For example, humidity sensor 14 b may be part of thermostat 14 t locatedwithin space 11 or building 19.

Various embodiments of air conditioning unit 10 or system 10 s alsoinclude a second sensor positioned and configured to sense a secondcondition, which may specifically be at the cooling coil 15 e. In anumber of embodiments, this second condition may be the formation offrost on cooling coil 15 e, for example, or may be a condition whereinfrost formation is possible or likely to occur or to have occurred. Insome embodiments, the second condition is a temperature, for example, of(or at) cooling coil 15 e (e.g., measured with temperature sensor 14 f)or a temperature of supply air 16 s (e.g., measured with sensor 14 edownstream of cooling coil 15 e). A temperature may be measured (e.g.,with sensor 14 f or at other locations), using a resistive thermaldevice (RTD) a thermocouple, a bulb containing a fluid that expands andcontracts with changing temperature, etc.

In various embodiments, the temperature at cooling coil 15 e, may bemeasured in a manner such that the temperature of cooling coil 15 e ismeasured directly (e.g., with the temperature sensor insulated from thenearby air), by measuring the temperature of air (e.g., supply air 16 sadjacent to the cooling coil 15 e), or the temperature sensor may bepositioned (e.g., in contact with or adjacent to and downstream fromevaporator 15 e) such that the temperature measurement is influenced bythe temperatures of both the cooling coil 15 e and the air. In someembodiments, an infrared detector or thermal imager may be used (e.g.,as sensor 14 d, 14 e, or both), for example, to detect changes insurface temperature (e.g., of cooling coil 15 e, for instance, resultingfrom insulating properties of frost formed on cooling coil 15 e).

In other embodiments, the second condition may be another indicator offrost formation on cooling coil 15 e. For example, the second conditionmay be an increase in pressure drop across cooling coil 15 e (e.g.,where frost may block flow of air 16 r or 16 s through cooling coil 15e), for instance, measured as a differential pressure between pressuresensors 14 d and 14 e, for example, at a constant or common speed of fan12 a or motor 13 a. In some embodiments, an absolute or gauge pressuremay be used, (e.g., at sensor 14 d or 14 e) instead of a measured (orcalculated) differential pressure. In other embodiments, pressure drop(e.g., across coil 15 e) may be detected from current, power, voltage,speed, or a combination thereof, of motor 13, fan 12 a, drive unit 15,or a combination thereof. In still other embodiments, the secondcondition may be frost formation on evaporator 15 e detected with anoptical sensor, (e.g., at sensor 14 d or 14 e) which may detect a changein emissivity, or reflectivity of cooling coil 15 e as (e.g., white)frost forms thereon, for example.

In other embodiments, actual frost formation may be detected with asecond sensor that detects the electrical insulating or heat insulating(or conducting) properties of the frost, detects the physical presenceor thickness of the frost, detects a change in sound, vibration orresonance produced by the frost, detects the weight of the frost, or thelike. In even other embodiments, the second condition may be detected bymeasuring the temperature or phase of refrigerant leaving cooling coil15 e, by measuring or detecting the pressure of the refrigerant, or bychanging (e.g., interrupting) the flow of refrigerant or by changing(e.g., increasing) the speed of fan 12 a and observing a response,(e.g., a change in temperature of evaporator 15 e, supply air 16 s, orboth, where the presence of frost on evaporator 15 e may cause it towarm more slowly or stay cold longer as the frost melts). In someembodiments, the first condition (e.g., humidity), the second condition(e.g., frost formation on evaporator 15 e), or both, may be detected bymeasuring the flow rate of condensation produced from evaporator 15 e,as further examples.

Various such embodiments include controller 14 that is in communicationwith the first variable-speed drive unit or system 15 and incommunication with the first sensor and the second sensor, for example.In many such embodiments, controller 14 is configured to cause the firstvariable-speed drive system 15 to change the speed of the firstelectrical motor 13 a in response to the first condition sensed by thefirst sensor and in response to the second condition sensed by thesecond sensor. It should be noted that, in the embodiment illustrated,the variable-speed drive system 15 is a separate component from motor 13a, but in other embodiments the variable-speed drive system 15 may bephysically attached to or integral with motor 13 a.

In a number of embodiments, controller 14 is configured to cause thefirst variable-speed drive system 15 to reduce the speed of the firstelectrical motor 13 a in response to an excessive humidity conditionsensed by the first sensor (e.g., within space 11, return air 16 r, orsupply air 16 s). Reducing the speed of motor 13 a, and thereby fan 12a, reduces the airflow rate through cooling coil 15 e causing coolingcoil 15 e and the air passing therethrough (e.g., supply air 16 s) tobecome colder. Colder air is less able to retain moisture or humidity,so the moisture in the air condenses (e.g., onto cooling coil 15 e,where it may be collected for disposal). In many embodiments, if coolingcoil 15 e becomes too cold (e.g., drops below freezing) then frost mayform on cooling coil 15 e rather than liquid water, or liquid watercondensation may freeze forming ice on cooling coil 15 e. (As usedherein, unless clearly otherwise, “frost” formed, for example, oncooling coil 15 e includes “ice” formed on cooling coil 15 e viafreezing of liquid water that has condensed on cooling coil 15 e andthen frozen.) Frost formation on cooling coil 15 e may reduce the heattransfer effectiveness of cooling coil 15 e, block the flow of air(e.g., return air 16 r) through cooling coil 15 e, cause structuraldamage to cooling coil 15 e or other parts of air conditioning unit 10or system 10 s, cause condensation to leak or travel to an undesiredlocation, potentially damaging other components or materials, or acombination thereof, as examples.

In some embodiments, for example, to avoid frost formation oraccumulation, controller 14 is configured to cause the variable-speeddrive system 15 to stop reducing the speed of the first electrical motor13 a. Further, in some embodiments, the controller 14 is configured tocause the first variable-speed drive system 15 to actually increase thespeed of the first electrical motor 13 a to avoid frost formation on thecooling coil 15 e. Such activities are described in more detail below.As used herein, avoiding frost formation includes preventing frost fromforming at all, as well as reducing the amount of frost that forms, forexample, in comparison with the amount of frost that would form (orwould have formed) if action to avoid frost formation had not beentaken.

Still further, some embodiments include a third sensor positioned andconfigured to sense a third condition within at least one of the space11 and the air (e.g., return air 16 r or supply air 16 s), and thisthird condition may be a temperature within at least one of the space 11and the air (e.g., return air 16 r or supply air 16 s), for example. Oneor more of sensors 14 c, 14 d, and 14 e, may be an example of this thirdsensor. Sensor 14 c is shown within thermostat 14 t, and may be the sametemperature sensor that is used to control the temperature of space 11.In the embodiment illustrated, thermostat 14 t is an example of a systemcontroller located within space 11. As used herein, a system controllermay be a thermostat, a setback controller, or another device into whicha user can input instructions for how unit 10 or system 10 s is tooperate. As illustrated, in some embodiments, a system controller (orthermostat) may include temperature sensor 14 c, humidity sensor 14 b,or both. Sensor 14 d is within return air 16 r, and sensor 14 e iswithin supply air 16 s, and sensors 14 d, 14 e, or both, may be (orinclude) temperature sensors (e.g., the third sensor described herein).

In some such embodiments, the controller 14 is in communication with thethird sensor and is further configured to forgo causing the firstvariable-speed drive system 15 to reduce the speed of the firstelectrical motor 13 a in response to the first condition sensed by thefirst sensor, if the third condition exceeds a threshold. Controller 14may be configured as such through software instructions, for example. Incertain embodiments, the threshold is a temperature, which may berelative to a temperature set point of the system controller (e.g.,thermostat 14 t). In certain embodiments, the threshold may be 2, 3, 4,5, 7, 8, 9, 10, 11, 12, 15, or 20 degrees (F or C) above the temperatureset point (e.g., of thermostat 14 t), for example. Thus, if thetemperature (e.g., within space 11 or return air 16 r) exceeds thethreshold, priority may be given to cooling space 11 rather thandehumidifying space 11. In other words, the system may be programmed orconfigured not to go into a dehumidification mode if the temperatureexceeds the threshold temperature.

In addition to the air conditioning systems and units, and controllersconfigured as described herein, other specific embodiments of theinvention include various methods, including methods of controllinghumidity within a space, methods of controlling an air conditioningunit, methods of reducing humidity, methods of reducing humidity whileavoiding freezing of a cooling coil, methods of controlling the speed ofa blower fan, and the like. FIG. 2 illustrates an example of a method,method 20, which may be a method of controlling humidity within a spacesuch as space 11, but also illustrates other methods in accordance withthe invention. Method 20 may be performed by air-handling or airconditioning unit 10, ventilation or air conditioning system 10 s, orspecifically by controller 14, as examples. In such examples, theairflow rate that is controlled may be the airflow rate of supply air 16s, return air 16 r, or both, for example. In many embodiments, method 20is automated, is computer controlled, or both. Further, in variousembodiments, method 20 is repeated a number of times, is continuous, orboth. And in some embodiments of method 20, humidity may be at leastpartially controlled, for example, in comparison with the prior art.

In the embodiment illustrated, method 20 includes providing or obtainingequipment (act or activity 21). For example, some embodiments include(at least) providing or obtaining an air-conditioning unit (e.g., 10)that includes a cooling coil (e.g., 15 e) and a variable-speed fan(e.g., 12 a). In many embodiments, the fan (e.g., 12 a) is positionedand configured to move air (e.g., return air 16 r, which becomes supplyair 16 s) through the cooling coil (e.g., 15 e) to the space (e.g., 11).FIG. 1 illustrates an example of such equipment. In a number ofembodiments, the equipment (e.g., motor 13 a, compressor 17 a and motor13 c, or a combination thereof) may initially, or at other times, beturned off (activity 22). In some embodiments, equipment may cycle on(e.g., in activity 26) and off (e.g., in activity 22) to controltemperature within space 11, for instance. On the other hand, in otherembodiments, speed, for example, of compressor 17 a, fan 12 a, or both,may be varied (e.g., in activity 26, activities 25 and 26, or inactivities instead of some or all of activities 22, 25 and 26) tocontrol the temperature within space 11, besides embodiments wherein theequipment cycles on and off (e.g., off in activities 26 and 22).

In various embodiments, for example, a temperature control routine(e.g., an example of which is represented by activities 22 to 27)operates to control temperature, unless conditions are such that ahumidity control routine (an example of which is represented byactivities 28 to 33) is allowed to take over and to reduce humidity(e.g., within space 11). In other embodiments, other routines to controltemperature may be used, such as variable capacity, variable speed,proportional control, variable air volume, or a combination thereof, asexamples. In some embodiments, when the humidity control routine (anexample of which is represented by activities 28 to 33) is not active,or is terminated due to a change in conditions (e.g., an increase intemperature or a reduction in humidity), then the system returns to thetemperature control routine (e.g., as represented by activities 22 to27), which in some embodiments, includes an increase in fan speed (e.g.,fan 12 a). In different embodiments, such an increase in fan speed maybe sudden, or may be gradual (e.g., incremental).

In many embodiments, a user (e.g., a person) enters or selects atemperature set point, for example, by setting a thermostat (e.g.,thermostat 14 t) or by entering a value into a system controller. Such aset point may be received by the equipment or controller (activity 23),for example, by thermostat 14 t, controller 14, or both. Such atemperature set point (e.g., received in activity 23) may be aparticular temperature, for example, in degrees F. (Fahrenheit) or C.(Centigrade or Celsius), for example, such as 72 or 75 degrees F. Insome embodiments, the set point temperature may be stored, for example,in controller 14. In some embodiments, the temperature set point may besubstantially constant, for example, throughout a particular day, andmay remain constant once set by a user until the user changes the setpoint or enters a new set point. In some embodiments, on the other hand,the temperature set point may change, for example, throughout aparticular day, for instance, to reduce energy consumption whenoccupants are not usually present, to provide different temperatures atnight than in the daytime, to reduce peak energy consumption at peakdemand times, to reduce electric bills where a demand charge is paid, toreduce electric bills where a higher rate is paid during high-demandtimes, or a combination thereof, or the like. Thus, in some embodiments,the temperature set point may be received (e.g., in activity 23) fromstorage, from a database, from another control device, from a formula orcalculation, or the like, besides a direct entry from a user entered atthe time of the change.

In various embodiments, a temperature within the space may be measured(activity 24). In many embodiments, measurements described herein may bemade automatically, continuously, or both, for example, using sensors(e.g., 14 b to 14 f), under the control of a controller (e.g.,controller 14), or both. In particular embodiments, for example,controller 14 or thermostat 14 t may measure temperature (e.g., anexample of activity 24) within space 11 using sensor 14 c, for instance.In different embodiments, temperature may be measured (e.g., in activity24) continuously, or in one or more discrete operations, for example.

In this embodiment, method 20 includes evaluating (activity 25) whetherthe temperature (e.g., measured in activity 24) exceeds the temperatureset point (e.g., received in activity 23). If not, then the equipment(e.g., motors 13 a, 13 b, and 13 c shown in FIG. 1) is (are) turned off(activity 22) or remain(s) off if already off, in some embodiments. Onthe other hand, if the temperature exceeds the set point (activity 25)then the equipment may be started, or may continue to operate if alreadyoperating (activity 26). For example, motors 13 a, 13 b, and 13 c may bestarted or may be allowed to continue to run. In some embodiments,motors 13 c and 13 b driving the compressor 17 a and the condenser fan12 b may be started first, and motor 13 a driving blower fan 12 a may bestarted after a short delay or after cooling coil or evaporator 15 ebecomes cool, for example, as determined by sensor 14 f and controlledby controller 14. In some embodiments, equipment may operate (activity26) for a discrete period of time, or a minimum period of time, forexample, for 10, 15, 30, 45, 60, 90, 120, 150, 180, 240, or 300 seconds,as examples.

As mentioned, method 20 may be a method that includes a temperaturecontrol routine in which the unit (e.g., 10) cycles on and off tocontrol temperature (e.g., within space 11). Other embodiments mayinclude a temperature control routine that varies one or more speeds,for example, of motor 13 c and compressor 17 a, to control temperature,to control airflow, or both. In some such embodiments, speeds of motors13 a, 13 b, or both, may be varied as well as motor 13 c, for instance.Temperatures may be controlled or the acts or activities described tothis point for method 20 may be in accordance with one of severaldifferent temperature control routines or methods known in the art.

In some embodiments of temperature control routines of method 20, atemperature deadband may be used (e.g., in activity 25). For example, insome embodiments, a two-degree temperature deadband is used, and theunit (e.g., 10) may be started (e.g., activity 26) when the temperaturein the space (e.g., 11) reaches a temperature of 1 degree (e.g., F. orC.) above the temperature set point (e.g., received in activity 23), andthe unit (e.g., 10) may be stopped (activity 22) when the temperature inthe space (e.g., 11) reaches a temperature that is 1 degree below thetemperature set point (e.g., received in activity 23). Other deadbands,for example, one half of one degree, or two degrees (F. or C.), may beused in other embodiments. While within in the deadband, the unit (e.g.,10) may remain off or operating, depending on what it was already doing,remaining in the same status to reduce the number of starts and stops ofthe unit (e.g., 10).

Many embodiments of the invention may include or utilize a threshold oran offset temperature (e.g., in addition to a temperature controlroutine), which may be evaluated in activity 27. In some embodiments,the offset temperature may be a particular number of degrees above theset point temperature (e.g., received in activity 23), for example, 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 15, 20, or 25 degrees (F. or C.)above the set point temperature. In some embodiments, the offsettemperature may be a fixed offset or threshold, while in otherembodiments, the offset temperature may be selectable by the user, forexample, entered into a system controller (e.g., thermostat 14 t), forinstance, as an absolute temperature (e.g., of space 11, for example, asmeasured by sensor 14 c) or relative to the temperature set point (e.g.,received in activity 23).

In some embodiments, if the temperature (e.g., within space 11, forinstance, as measured by sensor 14 c or 14 d) exceeds the offset (e.g.,as determined in activity 27), then the temperature control routine maycontinue to be followed (e.g., rather than starting a humidity controlroutine) to maximize effective temperature control. In some embodiments,for example, the equipment may continue to operate (e.g., repeatingactivity 26, for example, in the same mode or the same or higher fanspeed) until the temperature (e.g., of space 11) drops below the offsettemperature. In a number of embodiments, if the temperature (e.g., ofspace 11) exceeds the offset (e.g., as determined in activity 27), thenthe system (e.g., 10 s) or unit (e.g., 10) may give priority to reducingthe temperature (e.g., of space 11) rather than reducing humidity (e.g.,rather than entering or remaining in a dehumidification mode). In someembodiments, at least if humidity is excessive, fan speeds (e.g., fan 12a) may be higher if the temperature (e.g., within space 11) exceeds theoffset. In other embodiments, however, activity 27 may be omitted orskipped.

In certain embodiments, the blower (e.g., fan 12 a), compressor (e.g.,17 a), or both, may be started (e.g., in activity 26) at full speed. Insuch embodiments (e.g., of method 20), if the temperature exceeds theoffset (e.g., as determined in activity 27), then the equipment (e.g.,fan 12 a, compressor 17 a, or both), may continue to be operated(activity 26) at the full speed. In other embodiments, the blower (e.g.,fan 12 a) may be started (e.g., in activity 26) at less than full speed,for example, at 30, 40, 50, 60, 70, 80, or 90 percent of full speed. Insuch embodiments (e.g., of method 20), if the temperature exceeds theoffset (e.g., as determined in activity 27), then the fan speed (e.g.,fan 12 a) may be increased (e.g., in activity 26, 33, or anotheractivity), and the fan (e.g., fan 12 a) may be operated (e.g., inactivity 26) at a higher speed or at the full speed, as examples.

In some embodiments, the fan speed (e.g., fan 12 a) may be increased(e.g., in activity 26) immediately to full speed. In other embodiments,the fan speed (e.g., fan 12 a) may be increased (e.g., in activity 33)gradually or incrementally, for example, by 2, 3, 4, 5, 6, 7, 8, 9, 10,12, 15, 20, 25, 30, 40, or 50 percent of full speed or percent of thedifference between the current speed and the full speed. In otherembodiments, the speed (e.g., of fan 12 a) may be increasedcontinuously, for example, until full speed is reached, until thetemperature (e.g., within space 11) no longer exceeds the offset (e.g.,in activity 27), or until the temperature control routine calls formaintaining the same speed or reducing the speed. In some embodiments,the compressor (e.g., 17 a) may also initially be started at less thanfull speed, and its speed may be increased if the temperature (e.g.,within space 11) exceeds the offset temperature (e.g., in activity 27).

In various embodiments, if the temperature (e.g., of space 11, forexample, as measured in activity 24) exceeds the set point (e.g., asdetermined in activity 25) but is within the off set (e.g., asdetermined in activity 27), then the humidity may be measured (activity28). In some embodiments, humidity may be measured (activity 28) just ifthese conditions exist, while in other embodiments, humidity may bemeasured (activity 28) continuously or periodically, and suchmeasurements may be used or acted upon (e.g., in a humidity controlroutine) only under certain conditions, such as those described hereinor illustrated by method 20 or FIG. 2. In activity 28, humidity may bemeasured, for example, using one or more of sensors 14 b, 14 d, or (inparticular embodiments) 14 e, for example, within space 11, return air16 r, or (in particular embodiments) supply air 16 s. Absolute moisturecontent or humidity, relative humidity, dew point, another indicia ofhumidity, or the like, may be measured (e.g., in activity 28) orcalculated, as examples.

In the embodiment illustrated, as part of an example of ahumidity-control routine, method 20 also includes evaluating whether thehumidity level (e.g., measured in activity 28) is excessive (activity29). For example, the humidity level of the space (e.g., 11) or returnair (e.g., 16 r) may be considered to be excessive (e.g., in activity29) if it is a relative humidity that exceeds 25, 30, 35, 40, 45, 50,55, 60, 65, 70, 75 or 80 percent, as examples. In particularembodiments, a relative humidity between 45 and 65 percent is used(e.g., in activity 29), between 40 and 60 percent, between 50 and 60percent, or 55 percent specifically, for instance. In other embodiments,an absolute humidity, moisture content, or wet bulb temperature may beused (e.g., in activity 29 or in a humidity-control routine) rather than(or in addition to) a relative humidity. In embodiments wherein humidityis used (e.g., in activity 29), an actual value of humidity (e.g.,relative humidity) may be measured (e.g., in activity 28), which may becompared to a humidity threshold (e.g., in activity 29), for example,digitally. In some such embodiments, a user may be able to adjust orselect the humidity threshold, for example, through a system controlleror thermostat (e.g., 14 t). In some embodiments, a user may be able toselect the humidity threshold, for instance, between 40 and 60 percent.In other embodiments, a sensor (e.g., 14 b or 14 d) may only indicatewhether the threshold humidity is exceeded or not. In such embodiments,the threshold humidity may not be adjustable, or may only be adjustableby making an adjustment at the sensor, as examples.

As an example of a humidity-control routine, in a number of embodiments,method 20 includes measuring humidity (activity 28) using an automatedprocess to obtain a humidity measurement, and using an automatedprocess, using the humidity measurement (e.g., from activity 28) todetermine (e.g., in activity 29) whether to reduce the humidity (e.g.,in supply air 16 s, or space 11). In the embodiment illustrated, if thehumidity is not excessive (e.g., as determined in activity 29), then ifthe temperature (e.g., within space 11) continues to exceed the setpoint (e.g., as determined in activity 25), then the equipment continuesto operate (activity 26), for example, at the same fan speed (e.g., fan12 a). In some embodiments, if the fan is not already operating at fullspeed, or at normal speed, or if the fan speed has been reduced toreduce humidity, (e.g., as will be described below), then the fan speed(e.g., fan 12 a) may be increased (e.g., in activity 26) after it isdetermined (e.g., in activity 29) that the humidity is not excessive.

Still referring to FIG. 2, in this example of a humidity-controlroutine, if the humidity level is found to be excessive (in activity29), then the next act in the embodiment illustrated is to check thecooling coil (activity 30). As with other measurements described herein,in some embodiments, the cooling coil may be checked (activity 30) justat the time indicated, while in other embodiments, the cooling coil maybe checked (activity 30) continuously or periodically, and themeasurements or results of such checks may be used or acted upon onlyunder certain conditions, such as those described herein or illustratedby method 20 or FIG. 2. In activity 30, the cooling coil (e.g., 15 e)may be checked for example, using one or more of sensors 14 d, 14 e, or(in many embodiments) 14 f, for instance. In some embodiments, acondition (e.g., a second condition) at the cooling coil (e.g., 15 e)may be sensed or measured. In a number of embodiments, such a conditionmay be an indicator of frost formation on the cooling coil (e.g., 15 e)or an indicator that conditions exist wherein frost formation could oris likely to occur, as examples. Various examples of this secondcondition, and how they are sensed or measured are described herein,which provide a number of examples of systems and methods of checkingthe cooling coil (activity 30).

In various embodiments, in the humidity-control routine, a determinationis made (activity 31) whether the cooling coil (e.g., 15 e) is frozen orwhether conditions occur wherein freezing (e.g., of cooling coil 15 e)or frost formation thereon has occurred or is likely to occur. Thevarious decision acts or activities described herein (e.g., activities25, 27, 29, 31, or a combination thereof) may be performed by acontroller, such as controller 14, for example, which may be a digitalcontroller, for instance. Activity 31 may be performed, for example,using information obtained, measured, or sensed in activity 30. If thecooling coil (e.g., 15 e) has frozen, has frost formed on it, or hasdropped below a certain temperature, as examples, (e.g., as determinedin activity 31), in different embodiments, then the fan speed (e.g., fan12 a) may be increased (activity 33), for instance, to avoid furtherfrost formation or to melt frost that has formed. On the other hand, ifthe cooling coil (e.g., 15 e) has not frozen, does not have frost formedon it, or is above the certain temperature (or above a deadbandtemperature range), as examples, (e.g., as determined in activity 31)then the fan speed (e.g., fan 12 a) may be reduced (activity 32), forinstance, so that the temperature of the cooling coil (e.g., 15 e),supply air (e.g., 16 s), or both, will decrease, resulting in removal ofmore moisture from the supply air (e.g., 16 s) or resulting in supplyair (e.g., 16 s) having less moisture content.

The reduction of the blower or fan speed (e.g., fan 12 a) may mark theentering of a dehumidification mode, for instance, of air conditioningunit 10 or system 10 s. In some embodiments, the fan speed (e.g., fan 12a) may be decreased (e.g., in activity 32) gradually or incrementally,for example, by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 40,or 50 percent of full speed or of the current speed (e.g., for eachiteration of activity 32). In various embodiments, the temperature(e.g., within space 11) may be measured again (activity 24) and comparedto the set point (e.g., in activity 25, and the set point may have beenchanged in activity 23, for example, by the operator), and the fan(e.g., fan 12 a) may operate (e.g., in activity 26) at the new (reduced)speed (e.g., for a period of time, such as described herein). Afterthis, the temperature (e.g., measured in activity 24) may be comparedagain against the offset (e.g., activity 27), and if it is within theoffset, then the humidity may be measured (e.g., in activity 28) again,and evaluated (e.g., in activity 29). And if the humidity is stillexcessive (e.g., as determined in activity 29) the cooling coil may bechecked again (e.g., in activity 30), and if the cooling coil (e.g., 15e) is still not frozen (e.g., as determined in activity 31), then thefan speed (e.g., of fan 12) may be reduced further (e.g., in anotheriteration of activity 32).

This process may repeat, for example, in the humidity-control routine,until frost conditions have occurred (e.g., as determined in activity31) or until the temperature set point is reached (e.g., as determinedin activity 25). Further, a number of methods include using an automatedprocess, measuring a first temperature within the space (e.g., activity24), and the reducing of the speed of the fan (e.g., activity 32) isperformed only if the first temperature is below a first thresholdtemperature (e.g., determined in activity 27). In other embodiments, thespeed (e.g., of fan 12 a) may be decreased continuously, for example,gradually, for instance, until frost conditions have occurred (e.g., asdetermined in activity 31) or until the temperature set point is reached(e.g., as determined in activity 25).

Such a process may be automated, for example, using a digital oranalogue controller (e.g., controller 14). Such methods include (e.g.,using an automated process), dependent upon the humidity measurement(e.g., measured in activity 28), lowering the speed of the fan (e.g., inactivity 32) to decrease the cooling coil (e.g., 15 e) temperature, thusincreasing the latent component of energy absorption at the cooling coil(e.g., 15 e), resulting in a reduction of the humidity (e.g., in space11) relative to or in comparison with a humidity level that would haveresulted from not lowering the speed of the fan (e.g., 12 a). Further,method 20 also illustrates an example of a method of, using an automatedprocess, measuring a second condition (e.g., in activity 30) at thecooling coil, and using an automated process, controlling the speed(e.g., in activities 32, 33, or both) of the fan (e.g., fan 12 a) usingthe second condition (e.g., measured or sensed in activity 30) to avoidfrost formation (e.g., as determined in activity 31) on the cooling coil(e.g., 15 e).

Certain methods include repeating, at least a plurality of times, thelowering of the speed of the fan (activity 32), which may be performedin discrete increments (e.g., in iteration s of activity 32), and thespeed of the fan (e.g., 12 a) may be held substantially constant for aperiod of time for each of the distinct increments (e.g., in activity26). In some embodiments, the temperature of the cooling coil ismeasured (e.g., in activity 30) during each period of time, and thelowering of the speed of the fan (activity 32) is performed in asubsequent discrete increment only if the temperature of the coolingcoil (e.g., measured in activity 30) is above a first temperaturethreshold (e.g., as determined in activity 31). Even further, someembodiments further include raising of the speed of the fan (activity33), which may be performed in discrete increments (e.g., in iterationsof activity 33), and the speed of the fan may be held substantiallyconstant for a period of time for each of the distinct increments (e.g.,in activity 26). In some such embodiments, the temperature of thecooling coil (e.g., 15 e) is measured (e.g., in activity 30) during eachperiod of time, and the raising of the speed of the fan (activity 33) isperformed in a subsequent discrete increment only if the temperature ofthe cooling coil (e.g., measured in activity 30) is below a secondtemperature threshold.

In particular embodiments, as an example, the second condition that ischecked in activity 30, for example, is a temperature at (or of) thecooling coil (e.g., of coil 15 e, which may be sensed by sensor 14 f,for instance). In some embodiments, the speed of the fan (e.g., 12 a) iscontrolled (e.g., by controller 14) using the second temperature (e.g.,of the cooling coil, for instance, measured or sensed in activity 30) toavoid having the second temperature drop below freezing (e.g., below 32degrees F. or 0 degrees C., although in some embodiments, to account forvariations in temperature within coil 15 e, a higher temperature may beused, for example, 33, 34, 35, 36, 37, 38, or 40 degrees F., or 1, 2, 3,4, or 5 degrees C.).

In particular embodiments, for example, the cooling coil (e.g., 15 e) isdetermined (e.g., in activity 31) to not be frozen, or to be abovefreezing, if the temperature of the cooling coil (e.g., 15 e) is 35degrees F. or above. If that is the case (e.g., as determined inactivity 31), then the blower speed (e.g., fan 12 a) is reduced (e.g.,in activity 32) by 5 percent of the full or maximum blower speed (e.g.,of fan 12 a or motor 13 a). On the other hand, in this embodiment, thecooling coil (e.g., 15 e) is determined (e.g., in activity 31) to befrozen, below freezing, or too cold, if the temperature of the coolingcoil (e.g., 15 e) is less than 33 degrees F. If that is the case (e.g.,as determined in activity 31), then the blower speed (e.g., fan 12 a) isincreased (e.g., in activity 33), in this embodiment, by 5 percent ofthe full or maximum blower speed (e.g., of fan 12 a or motor 13 a). Inthis embodiment, if the cooling coil (e.g., 15 e) is determined (e.g.,in activity 31) to be less than 35 degrees, but 33 degrees or more (F.),then the blower speed (e.g., fan 12 a) is neither increased (e.g., inactivity 33) or decreased (e.g., in activity 32), but rather, is heldthe same.

The speed of the compressor (e.g., compressor 17 a, driven by motor 13c), and the speed of the condenser fan (e.g., fan 12 b driven by motor13 b) remain constant or at maximum during this process, in thisembodiment. Also in this embodiment, at each fan speed (e.g., fan 12 a,for example, obtained as a result of activities 32 or 33) the fan (e.g.,12 a) operates (e.g., in activity 26) for 30 seconds, or longer, forexample, if the cooling coil (e.g., 15 e) is determined (e.g., inactivity 31) to be less than 35 degrees, but 33 degrees or more (F.).Further, in other embodiments, other parameters may be used. Forexample, for the first threshold temperature, instead of 35 degrees F.,40, 38, 36, or 34 degrees F. may be used, or 6, 5, 4, 3, 2, or 1 degreesC. For another example, for the second threshold temperature, instead of33 degrees F. in the above example, 35, 34, 32, 31, or 30 degrees F. maybe used, or 2, 1, 0, −1, or −2 degrees C. may be used. Further, for thetime interval, instead of 30 seconds, 10, 15, 20, 25, 35, 40, 45, 60,75, 90, 120, 150, 180, or 240 seconds may be used in other embodiments.

In some embodiments, if the blower (e.g., fan 12 a) is operated at areduced speed (e.g., in the dehumidification mode) for a (first) periodof time to reduce humidity, then the blower speed may be increased for a(second) period of time to provide for adequate mixing of the air (e.g.,within space 11). In some embodiments, the first period of time (e.g.,the dehumidification mode), the second period of time, or both, mayinclude one or more iterations of activity 26, for instance. Forexample, in some embodiments, if the blower (e.g., fan 12 a) is operatedat a reduced speed (e.g., less than 50 percent of normal or full speed)for ten (10) minutes (e.g., in the dehumidification mode), then theblower speed may be increased to normal or full speed for five (5)minutes to provide for adequate mixing of the air (e.g., within space 11or building 19). In other embodiments, the first time period (e.g., ofthe dehumidification mode) may be 5, 8, 12, 15, 20, or 30 minutes, andthe second time period may be 1, 2, 3, 4, 6, 7, 8, 10, 12, or 15minutes, as other examples. Further, in other embodiments, the thresholdspeed (e.g., instead of 50 percent) may be 25, 30, 35, 40, 45, 55, 60,65, 70, 75, 80, 85, or 90 percent of normal or full speed, as otherexamples.

In different embodiments, the speed of the blower (e.g., fan 12 a) maybe increased suddenly to the normal or full speed (e.g., at the end ofthe dehumidification mode or when exiting the humidity-control routine),or may be increased gradually or in increments (e.g., such as throughactivity 33 described herein). In a number of such embodiments, afterthe second period of time, the system may return to a reduced speed(e.g., to the dehumidification mode) for another first period of time,for example, if the humidity (e.g., measured in activity 28 andevaluated in activity 29) remains excessive and the temperature (e.g.,measured in activity 24) remains above the set point (e.g., received inactivity 23 and compared to the temperature in activity 25). Forexample, the speed (e.g., of fan 12 a) may be reduced again in one ormore iterations of activity 32 or according to method 20 describedherein, as examples.

In some embodiments, in addition to mixing the air (e.g., within space11), periodically increasing the speed (e.g., of fan 12 a) to normal orfull speed (or to another higher speed) may remove some or all frost orice from the cooling coil (e.g., 15 e). Thus, in some embodiments wherethis occurs, activities 30 and 31 of checking the cooling coil andincreasing the fan speed if freezing exists, may not be necessary. Inother embodiments, activities 30 and 31 of checking the cooling coil andincreasing the fan speed if freezing exists may allow for longeractivity at reduced fan speeds, and thus greater or faster reduction inhumidity. In some embodiments, increasing the speed (e.g., of fan 12 a)to normal or full speed (or to another higher speed) may remove anyfrost or ice from the cooling coil (e.g., 15 e) that is not prevented byactivities 30 and 31 of checking the cooling coil and increasing the fanspeed if freezing exists. In other words, increasing the speed (e.g., offan 12 a) to normal or full speed (or to another higher speed) may serveas a back up for activities 30 and 31 of checking the cooling coil andincreasing the fan speed if freezing exists.

Further specific embodiments of the invention include, for example,particular methods of controlling humidity within a space using anair-conditioning unit (e.g., 10). Such an air conditioning unit mayinclude, for example, a cooling coil (e.g., 15 e) and a variable-speedfan (e.g., 12 a, which may include motor 13 a, variable-speed drive 15,or both), and the fan (e.g., 12 a) may blow air (e.g., return air 16 r,which becomes supply air 16 s) through the cooling coil (e.g., 15 e).Such methods include (e.g., in several possible sequences) receiving atemperature set point for the space (e.g., activity 23), measuring anactual temperature within the space (e.g., activity 24), measuring anactual humidity in at least one of the space and air drawn from thespace (e.g., 28), and evaluating whether the actual temperature withinthe space is within a predetermined offset of the temperature set point(e.g., activity 27). Such methods may also include evaluating (e.g., inactivity 29) whether the actual humidity (e.g., measured in activity 28)exceeds a predetermined humidity threshold, and if, and only if, theactual temperature within the space is within the predetermined offsetof the temperature set point (e.g., evaluated in activity 27), and theactual humidity (e.g., measured in activity 28) exceeds thepredetermined humidity threshold (e.g., evaluated in activity 29),lowering the speed of the fan (e.g., in activity 32, e.g., of fan 12 a)to reduce the humidity (e.g., within supply air 16 s, space 11, orboth).

Some of these methods further include monitoring at least a firstcondition of the cooling coil (e.g., activity 30) and increasing thespeed of the fan (e.g., activity 33, e.g., of fan 12 a) to avoidfreezing of the cooling coil (e.g., 15 e, e.g., as determined inactivity 31), and in particular embodiments, the monitoring of the firstcondition of the cooling coil (e.g., activity 30) comprises monitoringof a temperature at the cooling coil (e.g., via sensor 14 f). Inaddition, in a number of embodiments, the lowering of the speed of thefan (e.g., in a number of iterations of activity 32) includes (e.g., inthe following order), lowering the speed by a discrete speed increment(e.g., one iteration of activity 32), operating the fan (e.g., 12 a) ata substantially constant speed for a discrete increment of time (e.g.,one iteration of activity 26), measuring the first condition (e.g.,activity 30), and repeating the lowering of the speed by a discretespeed increment (e.g., repeating activity 32), operating of the fan(e.g., 12 a) at a substantially constant speed for a discrete incrementof time (e.g., repeating activity 26), and measuring of the firstcondition (e.g., repeating activity 30), until (e.g., as determined inactivity 31) the first condition (e.g., measured or sensed in activity30) reaches the first threshold value.

In some embodiments, the increasing of the speed of the fan (e.g., anumber of iterations of activity 33) comprises increasing the speed by adiscrete speed increment (e.g., one iteration of activity 33), operatingthe fan at a substantially constant speed for a discrete increment oftime (e.g., one iteration of activity 26), measuring the first condition(e.g., activity 30), and repeating the increasing of the speed by adiscrete speed increment (e.g., repeating activity 33), operating thefan at a substantially constant speed for a discrete increment of time(e.g., repeating activity 26), and measuring the first condition (e.g.,repeating activity 30), until (e.g., as determined in activity 31) thefirst condition (e.g., measured or sensed in activity 30) reaches thesecond threshold value. Further, in various embodiments, the firstcondition includes (or is) a temperature at the first coil (e.g.,measured at sensor 14 f), the first threshold value is a firsttemperature above freezing (e.g., 33 degrees F.) and the secondthreshold value is a second temperature (e.g., 35 degrees F.) above thefirst temperature. Still further, some such methods further includeincreasing the speed of the fan (e.g., 12 a) after a first time period(e.g., 10 minutes) to insure proper air distribution within the space(e.g., 11), and then returning after a second time period (e.g., 5minutes) to the lowering of the speed (e.g., activity 32) of the fan(e.g., 12 a) to reduce the humidity (e.g., within space 11).

Other embodiments of the invention may include other actions or aspectsfor example, for controlling of temperature within space 11, forexample. In some embodiments, the speed, for example, of fan 12 a,compressor 17 a, fan 12 b, or a combination thereof, may be varied tocontrol temperature, for instance. Further, various needs, objects,benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. However, theneeds, objects, benefits, advantages, solutions to problems, andelement(s) that may cause benefit, advantage, or solution to occur orbecome more pronounced are not to be construed as critical, required, oressential features or elements of the claims or the invention. Referenceto an element in the singular is not intended to mean “one and only one”unless explicitly so stated, but rather “one or more.” As used herein,the terms “comprises”, “comprising”, or a variation thereof, areintended to cover a non-exclusive inclusion, such that a process,method, article, or apparatus that comprises a list of elements does notinclude only those elements but may include other elements not expresslylisted or inherent to such process, method, article, or apparatus.Further, no element described herein is required for the practice of theinvention unless expressly described as “essential” or “critical”.

1. An air conditioning system for cooling and dehumidifying a spacewithin an enclosure, the air conditioning system comprising: a coolingcoil positioned within the system and configured to cool air to bedelivered from the air conditioning system to the space; a first fanpositioned and configured to move the air through the cooling coil andto the space; a first electrical motor connected to and configured toturn the first fan; a first variable-speed drive system configured andat least electrically connected to drive the first electrical motor; afirst sensor positioned and configured to sense a first condition withinat least one of the space and the air, wherein the first conditioncomprises a humidity; a second sensor positioned and configured to sensea second condition at the cooling coil; and a controller that is incommunication with the first variable-speed drive system and incommunication with the first sensor and the second sensor, wherein thecontroller is configured to cause the first variable-speed drive systemto change the speed of the first electrical motor in response to thefirst condition sensed by the first sensor and in response to the secondcondition sensed by the second sensor.
 2. The air conditioning system ofclaim 1 wherein the controller is configured to cause the firstvariable-speed drive system to reduce the speed of the first electricalmotor in response to an excessive humidity condition sensed by the firstsensor.
 3. The air conditioning system of claim 1 wherein the secondcondition is a temperature at the cooling coil.
 4. The air conditioningsystem of claim 1 wherein the controller is configured to cause thefirst variable-speed drive system to stop reducing the speed of thefirst electrical motor to avoid frost formation on the cooling coil. 5.The air conditioning system of claim 1 wherein the controller isconfigured to cause the first variable-speed drive system to increasethe speed of the first electrical motor to avoid frost formation on thecooling coil.
 6. The air conditioning system of claim 1 wherein thecooling coil is an evaporator coil, and wherein the air conditioningsystem further comprises, within a single enclosure for the airconditioning system, an expansion valve, a compressor, an electricsecond motor connected to and configured to turn the compressor, acondenser coil, a second fan configured to blow air through thecondenser coil, and an electric third motor connected to and configuredto turn the second fan.
 7. The air conditioning system of claim 1further comprising a third sensor positioned and configured to sense athird condition within at least one of the space and the air, whereinthe third condition comprises a temperature within at least one of thespace and the air, and wherein the controller is in communication withthe third sensor and the controller is further configured to forgocausing the first variable-speed drive system to reduce the speed of thefirst electrical motor in response to the first condition sensed by thefirst sensor, if the third condition exceeds a threshold.
 8. The airconditioning system of claim 7 wherein the third sensor comprises asystem controller located within the space, and the threshold isrelative to a temperature set point of the system controller.
 9. Abuilding comprising the air conditioning system of claim 1, wherein thebuilding forms the enclosure.
 10. A method of controlling humiditywithin a space, the method comprising at least: providing or obtainingan air-conditioning unit, the air conditioning unit comprising a coolingcoil and a variable-speed fan, wherein the fan is positioned andconfigured to move air through the cooling coil to the space; measuringhumidity using an automated process to obtain a humidity measurement;using an automated process, using the humidity measurement to determinewhether to reduce the humidity; using an automated process, anddependent upon the humidity measurement, lowering the speed of the fanto decrease the cooling coil temperature, thus increasing the latentcomponent of energy absorption at the cooling coil, resulting in areduction of the humidity relative to a humidity level that would haveresulted from not lowering the speed of the fan; using an automatedprocess, measuring a second condition at the cooling coil; and using anautomated process, controlling the speed of the fan using the secondcondition to avoid frost formation on the cooling coil.
 11. The methodof claim 10 further comprising, using an automated process, measuring afirst temperature within the space, and wherein the reducing of thespeed of the fan is performed only if the first temperature is below afirst threshold temperature.
 12. The method of claim 10 wherein thesecond condition is a temperature of the cooling coil and the speed ofthe fan is controlled using the second temperature to avoid having thesecond temperature drop below freezing.
 13. The method of claim 12further comprising, repeating at least a plurality of times the loweringof the speed of the fan, wherein the lowering of the speed of the fan isperformed in discrete increments, the speed of the fan is heldsubstantially constant for a period of time for each of the distinctincrements, the temperature of the cooling coil is measured during eachperiod of time, and the lowering of the speed of the fan is performed ina subsequent discrete increment only if the temperature of the coolingcoil is above a first temperature threshold.
 14. The method of claim 12further comprising, raising of the speed of the fan, wherein the raisingof the speed of the fan is performed in discrete increments, the speedof the fan is held substantially constant for a period of time for eachof the distinct increments, the temperature of the cooling coil ismeasured during each period of time, and the raising of the speed of thefan is performed in a subsequent discrete increment only if thetemperature of the cooling coil is below a second temperature threshold.15. A method of controlling humidity within a space using anair-conditioning unit, the air conditioning unit comprising a coolingcoil and a variable-speed fan, wherein the fan blows air through thecooling coil, the method comprising in any order: receiving atemperature set point for the space; measuring an actual temperaturewithin the space; evaluating whether the actual temperature within thespace is within a predetermined offset of the temperature set point;measuring an actual humidity in at least one of the space and air drawnfrom the space; and evaluating whether the actual humidity exceeds apredetermined humidity threshold; if, and only if, the actualtemperature within the space is within the predetermined offset of thetemperature set point, and the actual humidity exceeds the predeterminedhumidity threshold, lowering the speed of the fan to reduce thehumidity.
 16. The method of claim 15 further comprising monitoring atleast a first condition of the cooling coil and increasing the speed ofthe fan to avoid freezing of the cooling coil.
 17. The method of claim16 wherein the monitoring of the first condition of the cooling coilcomprises monitoring of a temperature at the cooling coil.
 18. Themethod of claim 16 wherein the lowering of the speed of the fancomprises in the following order, lowering the speed by a discrete speedincrement, operating the fan at a substantially constant speed for adiscrete increment of time, measuring the first condition, and repeatingthe lowering of the speed by a discrete speed increment, operating ofthe fan at a substantially constant speed for a discrete increment oftime, and measuring of the first condition, until the first conditionreaches a first threshold value.
 19. The method of claim 18 wherein theincreasing of the speed of the fan comprises increasing the speed by adiscrete speed increment, operating the fan at a substantially constantspeed for a discrete increment of time, measuring the first condition,and repeating the increasing of the speed by a discrete speed increment,operating the fan at a substantially constant speed for a discreteincrement of time, and measuring the first condition, until the firstcondition reaches a second threshold value.
 20. The method of claim 19wherein the first condition comprises a temperature at the first coil,the first threshold value is a first temperature above freezing and thesecond threshold value is a second temperature above the firsttemperature.
 21. The method of claim 15 further comprising increasingthe speed of the fan after a first time period to insure proper airdistribution within the space, and then returning after a second timeperiod to the lowering of the speed of the fan to reduce the humidity.